Cream butter, sugar, and vanilla together; add flour gradually until incorporated. (If dough is too dry, add water 1 tablespoon at a time.) Roll into 2 cyllinders and wrap in plastic OR place in gallon Ziploc bag, seal, and roll to a flat square. Chill at least 1 hour or up to 3 days. For cylinders, slice into 1/2″ rounds and arrange on baking sheet. For flats, split sides of bag and place dough on baking sheet, pierce (or roll pattern) on top and score into rectangles. Bake 375 degrees 10-12 minutes until edges are beginning to brown, but not the top. Remove to rack and allow to cool completely.